1. Field of the Invention
The present invention relates to a piezoelectric element configured of a lower electrode, a piezoelectric layer and an upper electrode; an actuator device fabricated by providing piezoelectric elements on a substrate with a vibration plate between the group of piezoelectric elements and the substrate; a liquid-jet head for ejecting droplets from nozzle orifices by use of the actuator device; and a liquid-jet apparatus.
2. Description of the Prior Art
An inkjet recording head with the following configuration has been put into practical use. In accordance with the configuration, parts respectively of pressure generating chambers communicating with nozzle orifices are constructed with a vibration plate. The nozzle orifices are those from which ink droplets are ejected. The vibration plate is distorted by piezoelectric elements, and thus ink in each of the pressure generating chambers is pressurized. Accordingly, ink droplets are ejected from each of the nozzle orifices. An inkjet recording head which is constructed, for example, in the following manner is among such inkjet recording heads. An even layer made of a piezoelectric material is formed on the entire surface of the vibration plate by use of a film-forming technique. Then, this layer made of the piezoelectric material is cut into shapes corresponding to the pressure generating chambers by the lithography method. Thereby, the piezoelectric elements are formed respectively in the pressure generating chambers in order that the piezoelectric elements can be independent from one another.
A piezoelectric element having a piezoelectric layer as follows is among piezoelectric elements used for such inkjet recording heads. The piezoelectric layer constitutes the piezoelectric element, and the half-value width of the (100) planes of the piezoelectric layer is defined as being not larger than 2.0 degrees when the face surface of the piezoelectric layer is measured by means of a wide-angled X-ray diffraction method (See the scope of claims and the like in Japanese Patent Laid-open Official Gazette No. 2001-203404, for example).
Although, however, the half-value width of the (100) planes of the piezoelectric layer is defined in this manner, information on an B-site atom is unknown. This brings about a problem that displacement characteristics, such as an amount of displacement, of the piezoelectric layer are still unknown. In other words, there is a problem that the deviation of the B-site atom can not be discriminated by the mere measurement of the half-value of the (100) planes for the following reasons. When the deviation of the B-site atom from the center of a crystal is smaller, an amount of displacement of the piezoelectric layer is also smaller. When the deviation of the B-site atom from the center is larger, an amount of displacement of the piezoelectric layer is also larger.
Incidentally, such problems are not limited to liquid-jet recording heads typified by inkjet recording heads, but are similarly present in other types of piezoelectric elements and other types of actuator devices using piezoelectric elements.